This invention relates to an insulation system and certain components thereof for use in rocket motors containing solid composite propellants.
In the construction of such rockets, the propellant is contained in a combustion chamber, which is separated from the forward compartment of the rocket by a bulkhead. The bulkhead is protected by a head-end insulator element and the combustion chamber walls are insulated with a suitable material. Some composite rocket propellants are based on carboxyl-terminated polybutadiene (CTPB) while others are based on hydroxyl-terminated polybutadiene (HTPB) binders. An important requirement of such rocket systems is the ability of the wall insulation to adhere to the combustion chamber and of the composite propellant to adequately adhere to the insulation system.
A sheet insulant which has been developed and successfully used with solid carboxyl-terminated polybutadiene (CTPB) propellant is a mixture of chrysotile asbestos fibers and floats dispersed in a CTPB polymeric binder, as taught in U.S. Pat. No. 3,943,208. The nature of this material will be described hereinafter in greater detail with reference to the specific description of the present invention.
A recent development in the art of solid rocket propellants is the introduction of hydroxyl-terminated polybutadienes (HTPBs), which have certain advantages over the CTPB propellants. With the advent of these propellants, it was hoped that HTPB insulant sheets could also be produced in the same manner as the CTPB sheets discussed above and having similar characteristics to the CTPB insulants, but which would be compatible with the HTPB propellants. Unfortunately, of a number of HTPBs tested, none provided insulant sheets which exhibited satisfactory shelf-life or bondability to the HTPB propellants.
It has therefore been an object of the present invention to provide a sheet insulant system which is a good thermal insulant and exhibits the necessary characteristics of bondability to HTPB systems.
Another object of the present invention is to provide an insulation process which will allow the positioning and bonding of the various insulating components to the rocket chamber in a single operation.